Atransform boundary occurs where two tectonic plates
collide into one another
move apart from one another
grind along each other
sit motionless against each other

It is the doctrine that the us had the right and duty to expand throughout north america. it just means they believed they had the right to expand westward and they did! they stated with the 13 colonies and then they kept moving gaining different territories throughout the years

Answer accretion;